The energy demand of a greenhouse is an important issue that needs to be addressed due to the high heat loss from its facades. Therefore, in every greenhouse building plan, calculating the heat loss of the building in advance based on the facade thermal transmittance is important to know the best U-value that must be used. In this study, a simple analytical investigation of energy consumption based on the facades U-value and its effort to maintain the energy sustainability by applying Photovoltaic (PV) panels to the surrounding greenhouse was presented. For the proposed greenhouse built in Loughborough, United Kingdom was found that the power generated by the PVs could cover the energy demand for a year with a façade U-value of 2 W/m2K to maintain the indoor temperature at 15°C whereas the monthly ambient temperature was no less than 4°C.